Power calculation wrong?

    • Autor

    Hello,

    I'm using this device in MQTT. For example, I got a message like this one:

    {'id': 0, 'a_current': 3.409, 'a_voltage': 231.2, 'a_act_power': 638.4, 'a_aprt_power': 787.6, 'a_pf': 0.84, 'a_freq': 50.0, 'b_current': 4.781, 'b_voltage': 230.6, 'b_act_power': 1008.4, 'b_aprt_power': 1101.8, 'b_pf': 0.92, 'b_freq': 50.0, 'c_current': 3.584, 'c_voltage': 232.3, 'c_act_power': 659.4, 'c_aprt_power': 831.2, 'c_pf': 0.83, 'c_freq': 50.0, 'n_current': None, 'total_current': 11.775, 'total_act_power': 2306.244, 'total_aprt_power': 2720.584, 'user_calibrated_phase': []}

    talking about phase A. I see 'a_current': 3.409, 'a_voltage': 231.2, ' and 'a_pf': 0.84,'. With these datas is easy to calculate Active and Reactive power:

    P = V * I * cos(phi) = 3.409 * 231.2 * 0.84 = 662.055
    S = V * I = 3.409 * 231.2 = 788.161

    Why, instead, the sensor give me the values 'a_act_power': 638.4 and 'a_aprt_power': 787.6 ???

    I tried with several messages and always seems to be wrong these datas. What's wrong? I'm missing something?

    Thanks for the reply

    Hi,

    Did you figure out what was going on? I have the same question myself.

    From what I observe in my installation, the 'pf' seems to be relatively stable, which I assume is calculated over a time period and updated accordingly. In other words, it seems to be an aggregated/averaged metric rather than instantaneous.


    Thanks!